Question

The graph of f(x)=3x what is the value of x when f(x)=9

Answer 1

`\{3\}`

Explanation:

Strictly speaking, we need to know the point of
`f(x) = 3x` intersecting
`f(x) = 9`. In other words, we need to solve the equality:

`3x = 9; \\ x = (9)/(3); \\ x = 3`

Here it is.